Iv'e had great success with some auto extension tubes, plus I only paid 60 on eBay for the set of 3 auto tubes, they aren't metal like I believe the Kenkos are, but they work great! It looks like you already have nice glass to pair up with too. I love my extension tubes with my cheapo 55-250 and a $7 over the lens flash diffuser from Amazon, I can handhold with my T2i and use the 10x magnification live view and stop down the aperture a ton, around 16 or higher and even use the built in flash, it is a great budget way to get really good macro and you already have good glass in the 70-200. Also, I really like using the tubes with my 55-250 because of how long the focal range is, I find it easier to focus using the zoom to get an approximate working distance, than focus by moving my hands while watching the magnified live view.

There is no quality loss when using tubes. It is only air inside of them and no glass. You loose 1-2 stops, and you have an extreme narrow depth of field, but you will get youre macro.

Lenses are generally optimised optically at infinity. I have the 50/2.5 macro. It has a floating element system, which means it changes optically as it focuses closer, so at 1:2 its not the same as at infinity. It is better when focused to 1:2, than focused at infinity with the EF25mm. It is also better at 1:1 with the life-size adapter that has glass than with my EF25mm extension tube. Simple lenses such as the nifty fifty simply rack the entire optical system further from the focal plane.

However, the (slight) reduction in optical quality may be acceptable. This will vary between lenses. My 70-200/4 (non-IS) is definitely less sharp than my 200/2.8 when used with the EF25mm extension tube. Indeed, I suggest that for the OP, extension tubes would meet his needs optically and financially, but a close-up lens would be easier when busy on the job.

I'll do some comparison shots in a few hours of the 50/2.5 with extension tube, life-size converter and with 250D closeup lens.

Question re: tubes... Realizing that of course - " extension tubes stretch lenses beyond their specification," how does the modest 12mm stack up? I fully realize this is a move which requires compromising... So how much of a falloff in IQ would I see with a 12mm tube vs the 250 close-up vs just sticking with what I have and cropping?

I'd love to hear more thoughts and see more images taken with tubes and close-ups. Because right now, the general consensus is to break my budget..

So, I will layout my general for the year gear plan so you can get a better idea of my dilemma, which may lead to more sound advice:

So, with all that said, a 12mm tube is about $90. Using existing tools and cropping will cost me $0.00. Some say the tubes are a great stop gap, others say they are rubbish. I'm trying to read between the lines here and it basically comes down to that question:

Question re: tubes... Realizing that of course - " extension tubes stretch lenses beyond their specification," how does the modest 12mm stack up? I fully realize this is a move which requires compromising... So how much of a falloff in IQ would I see with a 12mm tube vs the 250 close-up vs just sticking with what I have and cropping?

I think the only way you're going to know if it is going to work for you is to get the tube(s) from somewhere you can return it/them to no questions asked. Then you can play with it over the course of a few days, and see if it will work for you with your current lenses (and which ones), compare it to your crops, and you can gauge if the output is acceptable to your eye. If it isn't, you know you're looking at a lens. If it is, you're all set.

I don't think a 12mm tube is going to do very much in terms of stretching your lenses though.

Yeah, It does kind of boil right down to that...and if I am to do that, manswell just start with the cheapest option first!

There is no quality loss when using tubes. It is only air inside of them and no glass. You loose 1-2 stops, and you have an extreme narrow depth of field, but you will get youre macro.

Lenses are generally optimised optically at infinity. I have the 50/2.5 macro. It has a floating element system, which means it changes optically as it focuses closer, so at 1:2 its not the same as at infinity. It is better when focused to 1:2, than focused at infinity with the EF25mm. It is also better at 1:1 with the life-size adapter that has glass than with my EF25mm extension tube. Simple lenses such as the nifty fifty simply rack the entire optical system further from the focal plane.

However, the (slight) reduction in optical quality may be acceptable. This will vary between lenses. My 70-200/4 (non-IS) is definitely less sharp than my 200/2.8 when used with the EF25mm extension tube. Indeed, I suggest that for the OP, extension tubes would meet his needs optically and financially, but a close-up lens would be easier when busy on the job.

I'll do some comparison shots in a few hours of the 50/2.5 with extension tube, life-size converter and with 250D closeup lens.

Cheers

TY man...the more images I see from each option the better informed I am as I move forward!

Pick up this 25mm tube for $30. I picked up a used Canon one on ebay, but I'm sure they are equal. It cuts the MFD of most lenses in half. I use it with my EF100L, but it works great on any lens. I am a big fan of IS, so when you swap your old 70-200 for the mkll, your MFD will be 24" with IS. It ain't macro, but it's a damn fine close up. The IS and 24" distance will allow plenty of stability and light so you can get the DOF you want. What's $30 in the major scheme of things?

Here are some comparison shots:50mm 2.5 @ f8 and ISO 100. I used f8 as it appeared that the OP used something similar in the ring shots. f8 provides sufficient depth of field and a soft background. All focused on the centre of the same flower. Live view (so mirror locked up) and 2 sec self-timer.Large fine, downsized to 1020 pixels high (I have the original files)

1. 1.5 ft (min focus of 50mm f1.42. 1.5 ft with Canon 250D close up lens3. 0.89 ft (27cm) to give similar magnification (1:3)4. 0.75ft (23cm) 1:25. Focused at infinity with 25mm extension tube6. Set at similar magnification 1:2 with life size converter.The last two are in the next post.

Here 1000 pixel vertical crops of the original images.First the two photos at 1:3. 50mm focused at 1.5 ft with 250D, then 50mm focused at 0.89 ft (no close up lens)I note that the second photo is not focused at the same point as the first (bit of a rush over my lunchbreak!).

If you get tubes, Kenko is good, even the Opteka one linked is fine - they're all filled with the same air. Personally, I went with the Canon tubes - for macro work I wouldn't have, but since my main use is between a heavy and expensive body (1D X) and a much heavier and more expensive lens (600 II), I wanted to be sure of the mount strength.

been rethinking things....my 24-70v1...for some reason I have black listed this lens as the worst in my kit, leave it at home, and yeah lets dump/sell it... Why??? when I got my primes, I fell in love and wanted to use them...cause they rock...but, that 24-70...it's not nearly as bad as I had thought, and ---it can actually get pretty close, not macro close but close ---here's 2 just snapped... It was shot in mRAW (so if i bumped it to full RAW it would be even better) so keep that in mind, first one is uncropped, as close as i can get with the 24-70, second is a heavy crop...

So, maybe the answer in the hear and now is right in my bag! I may still snag a tube, just to see what they're like. But, I think I may be able to get by just fine with existing gear...which would give me the flexibility to snag a dedicated macro lens down the line.

I can't afford a true macro right now, so this is what I use for now: 55mm of cheap Chinese tubes (6$) and 30$ russian Industar 50-2 f3.5 (which is the smallest 50 I've ever seen) and chiped m42-EOS adapter (9$).

~100% crop

shot at f16 with of camera flash, iso 200. Basic sharpening and PP in LR. Don't know how it compares with real macro lens but for the price seems like a great deal to me.

I want to thank you all again for the lively debate and good advice. I was at my local shop yesterday looking for a smaller shoulder bag and had extra time so played around with the three options - tubes, close ups...and the 100mm 2.8L ...

And yeah, I can definitely say that the 100L made me wish I had extra $$$ in my account!!!!

Test shots in the camera store. Fun! I just picked up a backup body, so not till later in the season, but by august I think this lens will be in my bag....thanks again!